Effect of calcium alginate gel-bone morphogenetic protein-red bone marrow compound on the osteoinductivity / 中国组织工程研究

ABSTRACT

BACKGROUND: The bone marrow stromal cells in red bone marrow (RBM) are the non-specific bone growth factors,and the target cells of bone morphogenetic protein (BMP), and they have the activities of osteoinduction and osteogenesis.Injectable calcium alginate gel (CaAG) is a degradable biomaterial with good histocompatibility,it provides scaffold for the proliferation and adhesion of osteoblasts and chondroblasts,and it is good for the proliferation of new capillaries.OBJECTIVE:To prepare CaAG-BMP-RBM gel compound,and observe its osteoinductivity.DESIGN:A randomized controlled animal trial.SETTINGSDepartment of Orthopaedics,Shenzhen People's Hospital;Department of Orthopaedics,Union Hospital affiliated to Tongji Medical College,Huazhong University of Science and Technology.MATERIALSThe experiments were carried out in Shenzhen People's Hospital from February 2002 to February 2003.Twenty-seven pure SD rats, either male or female,weighing (200±20) g,were purchased from the Animal Experimental Center of Southern Medical University (No.SCXK2002-99).BMP was bought from Xijing Hospital affiliated to the Fourth Military Medical University of Chinese PLA.METHODS:The rats were randomly divided into three groupsCaAG-BMP-RBM group(n=9),CaAG.BMP group (n=9) and CaAG group (n=9).In the CaAG-BMP-RBM group,the rats were anesthetized,then 0.1 mL RBM collected from trochanteric section of fetour was added into the prepared CaAG-BMP compound (0.4 mL),sufficiently mixed,and then injected into posterior femoral muscle.The rats in the CaAG-BMP group and CaAG group were implanted with CaAG-BMP and CaAG into bilateraI posterior femoral muscles respectively.①The conditions of becoming conscious after anesthesia, incision healing, diet and activities were observed, the size and consistency of the implants and distribution of vessels were also observed.②The indexes were detected at 1,2 and 4 weeks after model establishment respectively,and 3 rats were used for each time point.The sections were observed under light microscope.and the activity of alkaline phosphatase (ALP) was determined.MAIN OUTCOME MEASURES: ①General conditions of animals and gross observation of the implants;②Histopathological observation;③ALP activities.RESULTS: All the 27 SD rats were involved in the analvsis of results.The rats became conscious at 4.6 hours after anesthesia,and they could eat normally;Hematom at incision disappeared.and the rats could move normally at 24 hours;No sign of infection at incision was observed at 72 hours;The incisions healed completely and suture shed after 2 weeks.The incisions were stage Ⅰ healing in all the 27 rats.①Results of gross observation of the implantsAt 1 week after implantation.the size of implant did not decrease and vessels in-grew in both the CaAG-BMP-RBM group and CaAG-BMP group;At 2 weeks,lhe quality was hard, and the section appeared as gray and white with deposition of bone-like tissues;At 4 weeks,a great amount of vessels in-grew,and there were many depositions of hard bone-like tissues.②Results of the histopathological observation under light microscopeIn the CaAG-BMP.RBM group.many mesenchymal cells aggregated, osteoblasts and chondroblasts proliferated actively al 1 week;The chondrocytes tended to mature with cartilage-like and bone-like matrixes at 2 weeks; Many osteocytes were observed and fibrous bone formed at 4 weeks.which were more then those in the other two groups.③Results of ALP activityAt 1.2 and 4 weeks after implantation.the ALP activities in the CaAG group [(0.179±0.018),(0.058±0.017).(0.027±0.018)IU/g] were lower than those in the CaAG-BMP-RBM group[(0.922±0.226),(1.169±0.249),(0.431±0.081)IU/g,P＜0.01);At 1 and 4 weeks,the ALP activities in the CaAG-BMP group[(0.447±0.015),(0.276±0.081)IU/g]were lower than those in the CaAG-BMP-RBM group (P＜0.05).CONCLUSION:The compound of CaAG-BMP-RBM possesses stable and lasting osleoinductivity.